Add multiple if statements in one cell?

Here is my current formula:
=IF($R2="KM",$O2*$S2,IF($T2="KM",$O2*$U2,IF($V2="KM",$O2*$W2,IF($X2="KM",$O2*$Y2))))

what that does is only gives me the result of one of the "KM" calculations. If one or all of R2,t2,v2,x2 contain "KM" I would like to return the total of the calculations. In other words add the 4 calculations together if applicable. If only one contained "KM" then fine, but if two or more contained "KM" I would like the result to be the x+x+x+x (x being the total of the calc in each IF statement. Make sense?