You can just add filters to the search
by specifying search.stress
as the ng-model
of other input fields with the values you want..
Example using radio buttons
<label><input type="radio" value="" ng-model="search.stress">any stress</label><br/>
<label><input type="radio" value="low" ng-model="search.stress">low stress only</label><br/>
<label><input type="radio" value="high" ng-model="search.stress">high stress only</label>
You can now filter for stress level in addition to the free text search
Demo at http://plnkr.co/edit/1MBRoq