If not all of the content is being returned in search you might consider rebuilding the search index to ensure the content is all index.
In regards to how search works: Spotlight search, the wildcard character * matches any number of non-whitespace characters when it is placed at the end of a word or within a word in the query. More details on search can be see in this document: https://community.jivesoftware.com/docs/DOC-169532#search_tips
Having said this, spotlight search should automatically append the wildcard character so if this is not the behavior you are seeing, i would recommend creating a private support case so that support can further review your site and look at logs to see if there are any errors in search.
Hope this helps.