I agree with Joe on the best approach, but if you have no control over the table you will need to use the substring, left and right functions of sql to process your searches.

if searching the 1st segment you can use the following
WHERE LEFT(ACCTNO, 2) = @searchValue
--or
WHERE SUBSTRING(ACCTNO,1,2) = @searchValue

2nd Segment use SUBSTRING
WHERE SUBSTRING(ACCTNO,4,3) = @searchValue
etc
The last segment you can use substring or RIGHT
WHERE SUBSTRING(ACCTNO,12,4) = @searchValue
--or
WHERE RIGHT(ACCTNO, 4) = @searchValue