[Moved to VBA] INDEX MATCH Mutiple worksheet and returns mutiple row

Hi,

Im trying to create a search function for a mutiple worksheet data(same format from A3:C19).
I.e

When I input the data i want to search in B3, the formula will search through all the worksheets in Column A and return multiple result of Column C in rows.

I.e. Search Dept : "A"
Results
A 2017
A 2017
A 2016
A 2016
A 2015
A 2015

I have attached my worksheet above for example.

Below is the formula I was using previously which it only searches from one sheet("2017"), now i need to split it to mutiple (2017,2016,2015 and so on......) sheet.

=IFERROR(INDEX(all!$A$4:$C$500, SMALL(IF(ISNUMBER((SEARCH($B$3,all!$A$4:$A$500))), ROW(all!$A$4:$C$500)-MIN(ROW(all!$A$4:$C$500))+1, ""),ROWS($B$6:B6)),3),"")


and if possible, can duplicate results be removed during the search instead of using advanced filter everytime after the search.