search_term dataLayer

// Fire this dataLayer event when a users performs a regular site search (in the top menu or search results page, etc).

<script>
    window.dataLayer = window.dataLayer || [];
    window.dataLayer.push({
     'event': 'search_results',
     'search_term': 'test',
     'search_result_count': '136'
     });
</script>