title: Search a letter in a list of words?
body: <p>I have an array called 'words' storing many words.</p>
  
  <p>For example:
  I have <code>'systematic', 'سلام','gear','synthesis','mysterious', etc.</code></p>
  
  <p>NB: we have <strong>utf8</strong> words too.
  How to query efficiently to see which words include letters <code>'s','m','e'</code> (all of them) ?</p>
  
  <p>The output would be:</p>
  
  <pre><code>systematic,mysterious
  </code></pre>
  
  <p>I have no idea how to do such a thing in PHP. It should be efficient because our server would suffer otherwise.e.</p>