"what seems to be the most relevant documents won't have all the exact words"
In which case it isn't relevant. I typed those words for a reason, any result not containing all three is not relevant by definition.
In which case it isn't relevant. I typed those words for a reason, any result not containing all three is not relevant by definition.
In other words, not a blanket 'the results for this query suck, but if I just stick my fingers in my ears and completely ignore one your words I get much nicer results so why don't I show you those?' - but a more intelligent presumption.
With, of course, the option to force the search to show specifically what you exactly searched for with no such helpful alternatives applied.
However, as of right now they only offer it for actual typos/spelling mistakes (like your example with the missing space) as opposed to semantically similar wordings.