title: Add values to User Meta Field within an array
body: <p>I want to have the following database entry for a User Meta Field:</p>
  
  <pre><code>meta_key =&gt; array ('value 1', 'value 2', 'value 3')
  </code></pre>
  
  <p>I tried to create the User Meta Field by the first push:</p>
  
  <pre><code>update_user_meta(
  $user-&gt;id,
      meta_key,
      array ($value1)
  );
  </code></pre>
  
  <p>Now I want to add new values to the array. But i don't want to lose the first. How is that possible?
  add_user_meta is not working because it adds new database-entries all the time.</p>