Add the ability to search all text fields of a request on Service Desk

Currently JIRA Service Desk seems to only search for the text in the Summary, Description and Comments of the request when searching for issues through the 'My Requests' page in the customer portal.

It'd be good to improve this search to all text fields (system's - such as Environment - as well as custom fields) as users won't always remember exactly what is described in the Summary.