This search normally operates under the assumption that you would like to match all words entered in the search field although not necessarily in the order they were entered. example: word1 word2 word3 entered into the search will require all results to have all 3 words in it.
If you want to have a match occur on any word that has been entered separate the words with the special operator OR. example: word1 OR word2 OR word3 entered into the search will return pages that have any combination of one or more of the words in it.
If the search should only show documents with an exact phrase surround that phrase with quote (") marks. example: entering "Exact Match" will only find documents that contact that exact phrase with the words in that order. Upper and lower case do not matter.