title: mongoengine query projection
body: <p>I want projection in mongoengine raw query , here is my query but it don't works</p>
  
  <pre><code>query  =  {'$or':[{'col1':{'$regex':srch_text}},{'col2':{'$regex':srch_text}},{'col3':{'$regex':srch_text}}]}
  
  projection = {'col4':0}
  test= Test.objects(__raw__=(query,projection))
  </code></pre>
  
  <p>p.s : without projection it works</p>
  
  <pre><code>test= Test.objects(__raw__=(query))
  </code></pre>