This should get you what you want:
1. Browse to whatever team you're looking for (e.g. go to Browse-->whichever sport-->Teams-->your team)
2. Click "Filters"
3. Under the "Notes" filter choose "AU*"
4. Click "Apply"
The filters that have the "*" next to them are wildcard searches Admin implemented earlier this year that will give you any cards that include that specific note plus any other notes, so in this case all autographed cards that have MEM, SN, or other notes (as long as the cards aren't missing notes which certainly happens from time to time).