By default in the VBulletin advanced search, if you type say three words:
Ajax Spade Orange
VBulletin will OR these and give results of any post with any of the three.

However, if you type this
Ajax AND Spade AND Orange
It will only provide search results which contain all of these words. This is a default setting and I'm not sure why it does not work. If I type it in with ANDs upon giving me results it clearly lists them as OR
Search: Keyword(s): Ajax OR Spade OR Orange

So, is there some special way to do this built in task?

Usually, the first thing to do when searching for a specific phrase is to enclose the keywords in quotation marks (ex. "Ajax Spade Orange") a-la Google, which is almost logically the same as Ajax AND Spade AND Orange, but technically (in the Niho forum at least), it will return an error with the following message, based on what I did:

Here, I typed "Fairy Tail", without the asterisk.

The search term you specified ("Fairy*Tail") is under the minimum word length (4) and therefore will not be found. Please make this term longer.

Honestly, I have no idea on why it does not work here, when in fact both Boolean Operators and Quotation Marks (") are supposed to work on vBulletin (click here (http://www.vbulletin.org/forum/showthread.php?t=253432) for more info). Niho only searches queries based on keywords.

However, you can still do a different kind of search, a sort of trick. In this case you would still enclose the phrase but instead of typing spaces, substitute the spaces with a question mark (?), which is a wildcard that represents one unknown character in that position.

Examples:
"ajax?spade?orange"

"ao?no?exorcist"

"Shakugan?no?shana"

Hope I helped you out in any way!