I have a page where I am using a Text Filter to filter a long (15K) list of clients in a Business Data List web part. The filter works fine for All and for an entered name, so long as the full name is entered. It would be much more effective if I could allow the user to enter part of a name, especially if there is a doubt about how that name is spelled. I have tried to edit the Connection properties, in SPD 2010, to change the comparison to Contains from equals, which it is clearly defaulting to, but I do not get the option. I cannot believe that this is not possible, but perhaps not in SPD ? JK
This article by Phil Wicklund suits your requirements. It uses a dataview web part and a form web part to do wild card searching of the DVWP content.
It's geared towards 2007, but the principles apply to 2010.