title: WordPress custom loop filter by meta_key and value with serialize data
body: <p>I am trying to run custom loop for Custom Post Type with filtering by some <code>meta_key</code> and <code>value</code></p>
  
  <p>Now simple meta value works fine but here I have a challenge with the below kind of serialized data (nested).</p>
  
  <p>I am using <a href="https://github.com/farinspace/wpalchemy" rel="nofollow noreferrer">wpalchemy</a> for meta box. <code>meta_key</code> for the post type is <code>_event_meta</code> and <code>value</code> is as below</p>
  
  <pre><code>a:9:{s:19:"ac_event_operations";a:1:{i:0;s:8:"Training";}s:18:"ac_event_positions";a:1:{i:0;s:10:"Supervisor";}s:18:"ac_event_employees";a:1:{i:0;s:2:"15";}s:13:"ac_event_date";s:10:"2017-06-15";s:19:"ac_event_start_time";s:5:"06:30";s:17:"ac_event_end_time";s:5:"07:00";s:14:"ac_event_place";s:6:"Office";s:18:"ac_event_organizer";s:4:"Jack";s:16:"ac_event_contact";s:4:"Rose";}
  </code></pre>
  
  <p>I am trying to filter <code>All Events</code> based on <code>ac_event_operations</code>, <code>ac_event_positions</code>, <code>ac_event_employees</code></p>
  
  <p>So for me, the challenge is to get events filtering with the value from above meta_keys. Here is the query I used but of course, it is not giving any result.</p>
  
  <pre><code>global $event_mb;
  $meta = get_post_meta( get_the_ID(), $event_mb-&gt;get_the_id(), TRUE );
  
  $paged    = ( get_query_var( 'paged' ) ) ? get_query_var( 'paged' ) : 1;
  $args     = [
      'post_type'      =&gt; 'event',
      'posts_per_page' =&gt; get_option( 'posts_per_page' ),
      'paged'          =&gt; $paged,
      'meta_query'     =&gt; [
          'meta_key' =&gt; '_event_meta',
          'value'    =&gt; '%ac_event_employees%',
          'compare'  =&gt; 'LIKE'
      ],
  
  ];
  $temp     = $wp_query;
  $wp_query = NULL;
  $wp_query = new WP_Query( $args );
  </code></pre>