XPath expression to perform 'keyword' query

I'm using the Sablorton (v1.0) XSL processor (which implements XSLT 1.0) 
(because I'm working from PHP, its XSLT extensions only support this 
processor).

I've written a database-like XML document and I'm trying to write a stylesheet 
to do a 'keyword' query (i.e. a query where the user supplies a number of 
keywords and the system returns all the records which contain those words).

The elements which correspond to database records are called 'item' (its a 
record library) and they contain other elements nested to various levels 
which contain all the data that the keyword search needs to examine.

In the stylesheet I'm using an <xsl:for-each select="//item[...]"> element but 
I'm completely stuck as to what XPath expression I could use to select the 
correct records.

My attempts are not worth posting!

Any thoughts would be very much appreciated.

Cheers,
Richard

PS. I may, if necessary move to the SAXON proessor (using XSLT 2.0) and use 
JSP instead of PHP.

 XSL-List info and archive:  http://www.mulberrytech.com/xsl/xsl-list