title: how to use 'like' instead of '=' in magento collection filter for custom module
body: <p>i have managed to do this with <code>addFieldToFilter</code> default functionality like this:</p>
  
  <pre><code>$collection-&gt;addFieldToFilter(
      array('first_name','last_name'),
      array($post['firstName'],$post['lastName'])             
  );
  </code></pre>
  
  <p>this is working when i print sql (this is just part from the whole statement being printed):</p>
  
  <pre><code>((first_name = 'r') OR (last_name = 't'))
  </code></pre>
  
  <p>now i am trying to understand how to use <code>'like'</code> instead of <code>=</code>.
  need some help in understanding that.</p>
  
  <p>your time and answers are highly appericiated thank you.</p>