title: get month from date meta query in WP_Query
body: <p>I store a date type stored by ACF Pro in custom meta "event_date" and I want to filter event by months with a query. The data is stored in </p>
  
  <p>I know that I need to use meta_query array like this :</p>
  
  <pre><code>$args['meta_query'] = array(
      array(
          'key' =&gt; 'event_date',
          'value' =&gt; ?,
          'compare' =&gt; '=',
          'type' =&gt; 'DATE'
      )
  );
  </code></pre>
  
  <p>But the <code>meta query</code> allows to compare with a full date. How to compare if the month variable (number 1 to 12) is the same that the <code>event_date</code> meta month ?</p>
  
  <p>Thanks</p>