partial match dictionary key(of tuples) in python

partial match dictionary key(of tuples) in python

I have a dictionary that maps 3tuple to 3tuple where key-tuples have some
element in common
dict= { (a,b,c):(1:2:3),
(a,b,d):tuple1,
(a,e,b):tuple,
.
(f,g,h):tuple,
.
.
.
tuple:tuple
}
now how can I find the values that match to (a,b,anyX) in a dictionary ie
(1:2:3) and tuple1
this is computer generated and very large thus, it takes effort to
determine anyX.
so, any good ways I can do this?