Yes this produces the “desired” 
pattern. Thks
q = [{
{:"$1", :"$2", :"$3", :_},
[{:orelse, {:==, :"$2", {:const, id}}, {:==, :"$3", {:const, id}}}],
[{{:"$1", :"$2", :"$3"}}]
}]
with:
q =
Ex2ms.fun do
{ch, e, r, _} when e == ^id or r == ^id -> {ch, e, r}
end
