Modifying a sumproduct formula to search for words in a cell

My current formula is this:

=SUMPRODUCT((Str311A=1)*(Str311C=15)*(Str311G<>" DM "),Str311L)

All the items starting with Str311 are formula's associate with a name. What I'm trying to do is add one more factor into the formula. I need it to look in column I for any cell that contains the words L/S. I tried modifying the formula to this but it does not work:

SUMPRODUCT((Str311A=1)*(Str311C=15)*(Str311I="*L/S*")*(Str311G<>" DM "),Str311L)

The formula contained inside the names are:

Str311=OFFSET(Outlet!$A$1,MATCH("STORE # 163311",Outlet!$A:$A,0)-1,0,MATCH("TOTAL FOR STORE : 163311 SAN MARCOS",Outlet!$A:$A,0)-MATCH("STORE # 163311",Outlet!$A:$A,0)+1,1)

Str311A=OFFSET(Str311,0,0)

Str311C=OFFSET(Str311,0,2)

Str311I=OFFSET(Str311,0,8)

Str311G=OFFSET(Str311,0,6)

What I need is a way to modify my original formula to now also only match cells that contain the phrase L/S. The phrase can be located at the beggining, middle, or end of the cell characters. Thanks in advance for any help that can be offered.

TRy:

SUMPRODUCT((Str311A=1)*(Str311C=15)*Isnumber(Search("L/S",Str311I))*(Str311G<>" DM "),Str311L)