In my application, I have two custom post types: ‘session’ and ‘speaker’. For the ‘session’ post type, I have added a custom field ‘_session_speakers’ which stores an array of one or more ‘speaker’ post type ids associated with the post. So the meta_value for the ‘_session_speakers’ meta_key looks something like this:

a:2:{i:0;s:2:"40";i:1;s:2:"15";}

I’m trying to implement a speaker search so users can search for all sessions by a particular speaker. I can get an array of speaker ids that match the search keyword as follows:

$speaker_args = array(
  'numberposts' => -1,
  'posts_per_page' => -1,
  'post_type'       => 'speaker',
  'post_status' => 'publish',
  'fields' => 'ids',
  's' => $keyword
);
$speaker_ids = get_posts($speaker_args);

Then I’d like to take that array and query the session posts to find all sessions that have any of the speaker ids in the ‘_session_speakers’ field. I’ve tried the following, but it does not return any results even though $speaker_ids contains values:

$args = array(
  'numberposts' => -1,
  'posts_per_page' => -1,
  'post_type' => 'session',
  'post_status' => 'publish',
  'meta_query' => array(
    'relation' => 'AND',
    'search_clause' => array(
      'key' => '_session_speakers', 
      'value' => $speaker_ids, 
      'compare' => 'IN' 
    )
  )
);
$sessions = new WP_Query($args);

Any thoughts on how I can accomplish this?