For three events \( A, B, \) and \( C \) of a sample space, if
\[
P(\text{exactly one of A or B occurs}) = P(\text{exactly one of B or C occurs}) = P(\text{exactly one of C or A occurs}) = \frac{1}{4}
\]
and the probability that all three events occur simultaneously is \( \frac{1}{16} \), then the probability that at least one of the events occurs is