I'd like to suggest an advanced option which will perform search in a manner of displaying results of ayas in which KEYWORDS from the search textbox are found, but not exact phrases (e.g. splitting the string into parts separated by blank and performing search for every part).
It might be confusing for some, but anyway, operators as (1)OR and (2)AND (maybe even NOT) can be added too, so that it provides:
1. to display all ayas which contain any of the keywords one is searching for
2. to display all ayas containing all of the keywords.