How to get the exact search results depending on metadata property ?

Hello

We have a metadata property known as PartNo, in the XSLT display name is Part #. When I enter condition as Part # Contains 19SPA, it returns all those items which contains( 19SPA/19SPA1/219SPA312 etc) but it wont return the items with which contains valus like  as 319SPA.

Please let me know how can I do this? We are using out of box SharePoint 2010 Document Center Search Web Part .

Avian