Achieving a polynomial that maps from $GF(p^q)$ to {0,1} with the same probability

Question

I am using an arithmetic circuit, which can compute polynomials over the field $GF(p^q)$.

I need a polynomial that maps any element from the field to an element from $\{0,1\}$, I need that the range will distribute uniformly in $\{0,1\}$, i.e. that the number of elements that are mapped to $0$ is equal to the number of elements that are mapped to $1$.

(Remember that an arithmetic circuit composed of $+$ and $\times$ gates.