When doing a Keyword, Global, or 'for text' search for part of a word, the expected results may not get fully returned. For example when searching for 'serv', partial of 'server', the search does not return all results like it would for 'server'.
If you are trying to get results for 'server', and using the word 'serv', your search string would need to be 'serv*' in order to retrieve the right results.
ServiceNow documentation pages on search wildcards:
The Porter word stemming algorithm adopted in ServiceNow: