Search for custom field

How can we search for a value from the custom fields?

We have ‘billing_leerlingnr’ as a custom field. We try to find this value in the WooCommerce order search, but is doesn’t show any results:

add_filter( 'woocommerce_shop_order_search_fields', 'VF_search_custom_fields' );

function VF_search_custom_fields( $search_fields ) {
    $search_fields[] = '_billing_leerlingnr';
    return $search_fields;
}

Is there a solution to be able to show the custom data after search in Woocommerce > Orders?

add_filter( 'woocommerce_shop_order_search_results', 'VF_search_leerlingnr_field', 10, 3 );

function VF_search_leerlingnr_field( $order_ids, $term, $search_fields ) {
    global $wpdb;

    $query = $wpdb->prepare(
        "SELECT post_id FROM {$wpdb->postmeta} WHERE meta_key='_th_wccl_customized_fields' AND meta_value LIKE %s",
        '%' . $wpdb->esc_like( $term ) . '%'
    );

    $results = $wpdb->get_col( $query );

    if ( $results ) {
        $order_ids = array_unique( array_merge( $order_ids, $results ) );
    }

    return $order_ids;
}