This is the solution I worked out to search for a value in another worksheet and look up a value in a cell that is offset from the search target.
If $L$4 contains the client identification number "1251", the MATCH portion of this formula finds 1251 in Pivot_Sheet, column A, and the MATCH function evaluates to the row number of the target. Since I want the 3rd item in the list for each client, I add +2 to the row number from MATCH.
The first data column in a series of columns is 2 columns to the right of the target. The "+2,2" portion of the OFFSET returns the value that is 2 columns down from the search target and 2 columns to the right. Resolved!