title: WP_Query search by meta_key value
body: <p>I have a meta field "a" with a1, a2, a11 multiplie values, etc.</p>
  
  <p><strong>get_post_meta(id, 'a'); displayed: Array array ([0] => a1 [1] => a6)</strong></p>
  
  <p>I do search by this code</p>
  
  <pre><code>array(
  'key' =&gt; 'a',
  'value' =&gt; 'a1',
  'compare' =&gt; 'LIKE'
  ),
  </code></pre>
  
  <p>But there was a problem, LIKE does not exact search and coincidence. at a1 value records with the field a11 are also displayed. How it is possible to correct it that search was precisely on a1 to value?</p>
  
  <pre><code>'value' =&gt; 'a1',
  'compare' =&gt; '='
  </code></pre>
  
  <p>And</p>
  
  <pre><code>'value' =&gt; array('a1'),
  'compare' =&gt; 'IN'
  </code></pre>
  
  <p>don't work. nothing is displayed</p>