title: How to manipulate my string using regex in php?
body: <p>I have a string as below</p>
  
  <pre><code>$str = '"Mark Zuckerberg" facebook "A social utility connecting friends" profile';
  </code></pre>
  
  <p>I want it to be manipulated as follows</p>
  
  <pre><code>$output = '"Mark Zuckerberg" OR facebook OR "A social utility connecting friends" OR profile';
  </code></pre>
  
  <p>What I am trying to have in output is all the units combined with OR in between them. Here a unit is wither a single word when its not in double quotes or the complete string that falls within the single quotes.</p>
  
  <p>I wanted to try with preg_replace. But am unable to get a correct regular expression to match. Kindly help!</p>