Search results for ACF data

Question

Is it possible to write a query to search for data from one custom field only? I have a CPT called 'lectures' and I only want to search for data that is in the custom field called 'keywords' I have this:

<?php
        $args = array(
            'post_type' => 'lectures',
            'order' => 'ASC',
            'posts_per_page' => -1,
            'meta_key' => 'keywords'
            
        );
        $query = new WP_Query($args);
        while ( $query -> have_posts()) : $query -> the_post();

    ?>

but it is not working. So if someone searches for 'Operant Conditioning' (one of the terms in the keywords ACF). I want any CPT with those 'keywords' (from the ACF) to show in results. I cannot add a specific keyword as there will be hundreds

Answer 1

This worked for me:

<?php
 if($_GET['module_search'] && !empty($_GET['module_search']))
     $keywords = $_GET['module_search'];
?>

<!-- Set args for search of cpt -->
            <?php
                $args = array(
                    'post_type' => 'lectures',
                    'order' => 'ASC',
                    'posts_per_page' => -1,
                    'meta_query' => array(
                      'relation' => 'OR',
                         array( 
                         'key' => 'keywords', // name of custom field
                         'value' => '[[:<:]]'.$keywords.'[[:>:]]', // matches exaclty "123", not just 123. This prevents a match for "1234"
                         'compare' => 'REGEXP'
        )
    )
                    
                );
                $query = new WP_Query($args);?>```