I think that you'll need to generate several find requests with inequality operators to get what you need.
A week represents a 7 (or 5 week day) range of dates. So each record being searched will have a date range of Date1...Date2 and the week specified will have a date range of DateA...DateB
1) You want to find any record where Date1 falls between DateA and DateB
2) any record where Date2 falls between DateA and DateB
3) any record where DateA is after or equal to Date1 and DateB is Before or equal to Date2
Examples. DateA...DateB might be 5/19/2013...5/25/2013
A script can take a Date entered/selected in a global date field for DateA, add 7 to compute DateB and then generate 3 find requests in a single find to find records for cases 1, 2 and 3 above.
Enter Find Mode 
Set Field [YourTable::Date1 ; YourTable::gDateA & "..." & gDateA + 7 ]
Set Field [YourTable::Date2 ; YourTable::gDateA & "..." & gDateA + 7 ]
Set Field [YourTable::Date1 ; "<" & YourTable::gDateA ]
Set Field [YourTable::Date2 ; ">" & YourTable::gDateA + 7]
Set Error Capture[on]