I have a problem with how to search for data according to keywords

this is my controller

protected $subCategori;
    protected $categori;

    public function __construct()
    {
        $this->subCategori = new SubCategoriModel();
        $this->categori = new CategoriModel();
    }
    public function index()
    {
        $currentPage = $this->request->getVar('page_page') ? $this->request->getVar('page_page') : 1;
        $keyword = $this->request->getVar('keyword');
        if ($keyword) {
            $this->subCategori->search($keyword);
        } else {
            $this->subCategori;
        }
        $data = [
            'menu' => 'subCategori',
            'subCategori' => $this->subCategori->getAll(),
            'page' => $this->subCategori->paginate(4, 'page'),
            'pager' => $this->subCategori->pager,
            'currentPage' => $currentPage
        ];
        if (session()->get('logged_in') != TRUE) {
            return redirect()->to('/admin/login');
        } else {
            // $data = ['categori' => $this->categori->findAll()];

            return view('subCategori/index', $data);
        }
    }

this is my model

 protected $table            = 'sub_categori';
    protected $primaryKey       = 'id';
    protected $useAutoIncrement = true;
    protected $returnType       = 'object';
    protected $allowedFields    = ['id_categori', 'nama_sub_categori', 'created_at', 'updated_at'];
    protected $useTimestamps = true;

    function getAll()
    {
        $builder = $this->db->table('sub_categori');
        $builder->join('categori', 'categori.id = sub_categori.id_categori ');
        $query = $builder->get();
        return $query->getResult();
    }
    public function search($keyword)
    {
        $builder = $this->builder();
        $builder->join('categori', 'categori.id = sub_categori.id_categori ');
        $builder->like('nama_sub_categori', $keyword);
        return $builder;
    }

this is my View

<?= $this->extend('admin/template') ?>

<?= $this->section('content') ?>

<main class="col-md-9 ml-sm-auto col-lg-10 px-md-4 py-4">
    <nav aria-label="breadcrumb">
        <ol class="breadcrumb">
            <li class="breadcrumb-item"><a href="/admin/dashboard">Home</a></li>
            <li class="breadcrumb-item active" aria-current="page">Sub Categori</li>
        </ol>
    </nav>
    <a href="<?= base_url('admin/addCategori') ?>"><button type="button" class="btn btn-dark mt-3 mb-2">Add Data</button></a>
    <div class="row">
        <div class="col-5">
            <form action="" method="post">
                <div class="input-group mb-3">
                    <input type="text" class="form-control" placeholder="Masukan Data kategori" name="keyword">
                    <button class="btn btn-outline-secondary" type="submit" name="submit">Cari Data</button>
            </form>
        </div>
    </div>
    </div>

    <table class="table table-bordered">
        <thead>
            <tr>
                <th>No</th>
                <th>Categori</th>
                <th>Sub Categori</th>
                <th>edit</th>
                <th>delete</th>
            </tr>
        </thead>
        <tbody>

            <?php $no = 1 + (4 * ($currentPage - 1)); ?>

            <?php foreach ($subCategori as $r) : ?>
                <tr>
                    <td><?php echo $no++ ?></td>
                    <td><?php echo $r->nama ?></td>
                    <td><?php echo $r->nama_sub_categori ?></td>
                    <td><a href=""><button type="button" class="btn btn-warning">Edit</button></a></td>
                    <td>
                        <form action="" method="post">
                            <?= csrf_field() ?>
                            <input type="hidden" name="_method" value="DELETE">
                            <button type="submit" class="btn btn-danger" onclick="return confirm('Apakah anda Yakin')">Hapus</button>
                        </form>
                    </td>
                </tr>
            <?php endforeach ?>
        </tbody>
    </table>
    <?= $pager->links('page', 'admin_pagination') ?>

    <footer class="pt-5 d-flex justify-content-between">
        <span>Copyright © 2019-2020 <a href="https://themesberg.com">Themesberg</a></span>
        <ul class="nav m-0">
            <li class="nav-item">
                <a class="nav-link text-secondary" aria-current="page" href="#">Privacy Policy</a>
            </li>
            <li class="nav-item">
                <a class="nav-link text-secondary" href="#">Terms and conditions</a>
            </li>
            <li class="nav-item">
                <a class="nav-link text-secondary" href="#">Contact</a>
            </li>
        </ul>
    </footer>
</main>
<?= $this->endSection() ?>

what I expected when I searched for data according to the data I was looking for.
example;I looked for clothes data but all the data came up.
and also when searching for data that does not exist