Three squares $ABCD$, $BEFG$, and $EHIK$ are equal in area, each with side length $s$. They are arranged in a horizontal row, sharing side $BC$ with $BE$ (so $B$ is common) and side $EF$ with $EH$ (so $E$ is common). Point $M$ is the midpoint of side $AD$ of square $ABCD$ and point $N$ is the midpoint of side $IK$ of square $EHIK$. What is the ratio of the area of the shaded pentagon $MABFN$ to the sum of the areas of the three squares?