"OR" condition on form search

Hello
How can I use “Or” condition in form search? That is, I either want the user input to search on col a or col b

<form action="" method="POST"><input name="loc" type="text" value="Help text" />
<input type="submit" value="Filter" />  <a href="http://merademo.asia/employertable/">Show All</a></form>
</br>
[cfdb-table form="Employerprofile" filter="Location~~/.*$_POST(loc).*/i&&Location~~/.*$_POST(loc).*/i"]

https://wordpress.org/plugins/contact-form-7-to-database-extension/