When using search forms with filters how do I change the 'Show all' to 'Search the whole table'

Question

I have a website i am working on that uses a plugin that is a database of people. The plugin also features a search facility where you can type search terms then choose options from dropdown menus.

The dropdown menu shows the defined fields set through the plugin, such as job title, experience, name, skills etc. There's also a list item named 'Show all' which basically resets the search to just show all the members in the table.

My question is... can you change that (show all) so instead of resetting to show all the members, type a search term that searches all the table and the results show each record with that given search term (but searching in multiple fields). An example would be something like this, just so it makes more sense :-)

Existing scenario

Search by 'Job title' > Designer = returns results with just designer

Ideal scenario

Search by 'All members' > Designer, 3 years of experience, programmer = returns results containing just those elements. I have contacted the developer of this plugin but has no plans to develop it further at this time.

Can anyone help with this? i'm no programmer however have handled php in web forms etc so not a total newbie! Would it be a case of declaring a variable containing a query to the database to search all fields based on the entered value? Then set that variable to query the db when selected as part of the search. Seem to have the theory just not the ability to convert to code!

Thanks in advanced! Michael