title: Django limit_choices_to for multiple fields with "or" condition
body: <p>I am trying to limit choices for a field, by checking values of the two columns, 'share_holder' and 'distributor'. If any of them is true, then I want that choice. </p>
  
  <p>With below version, I only got choices satisfying both conditions ('share_holder': True AND 'distributor': True). </p>
  
  <pre><code>limit_choices_to={'share_holder': True, 'distributor': True}
  </code></pre>
  
  <p>However, I need choices for ('share_holder': True OR 'distributor': True). </p>