Just for info - the decision on whether to treat space separated words as a string went the other way with the Search and Highlight plugin.
Some people will expect space separated multiple terms to be treated as separate words. Other people will want the words to be treated as a string for exact matching.
It would be nice if you split the words and highlight each term individually in the text. If the words are >>too far away from each other, maybe you can shorten the text between them using
[…].
I was pleased when the Search and Highlight plugin was recently altered to only match if the entire space separated string was found, this was because I was often getting literally hundreds and sometimes a few thousands of hits with commonly used words - in cases where the string itself would have given only tens of hits.
There is not a right way or a wrong way - it depends on what the user is trying to do.
It is possible for the person wishing multiple words to be treated as individual words to perform multiple searches rather than enter them all at the same time but this might not be the desired result if they specifically want to see all words highligted at the same time.
A person wishing to see the words treated as a string can in some cases cope if the search treats the words separately but may find it hard to spot the cases they wanted to see ( the first word followed directly by the second one ) against a backdrop of many times more results where only one of the words was found.
Again no wrong or right way - I am just highlighting the inconsistencies here with various search plugins and the fact that one plugin has recently changed behaviour in the opposite direction to the change in behaviour being requested here.
Here is the search and highlight discussion - the one that went in the other direction to the change request in the above thread.