I need some help please. This is what I have:

K L
4 Type ISO
5 Size 4x4
6 Thickness 3

In column K i have a list of warehouses that we have inventory in and L is
the search criteria that the salesman use to find what is available in out
100's of warehouses nationwide. This is the calculation that I am using for
the salesman to find out what warehouses have the specific material:

{=SUM(IF(Capitol!$B$13:$B$15=$L$4,IF(Capitol!$C$13 :$C$15=$L$5,IF(Capitol!$D$13:$D$15=$L$6,IF(Capitol !$A$13:$A$15,1,0)))))}

I have this calculation for each of our warehouses and it tells me with a #1
or whatever when that material is in which warehouse......... How can I
change the calculation to say bring up only the type, or only the size? Like
the salesmen want to be able to search with any 1 of the 3 criteria, and then
add a 2nd criteria to narrow the 1st search down and so on.. does that make
sense? I'm sure its easy and i'm overlooking it and making it harder than it
needs to be... Any help will be greatly appreciated...