Several MATLAB plot types require the ‘Z’ argument to be a matrix.
One way of creating it is to interpolate it, and one way of doing that is this example where ‘x’, ‘y’ and ‘z’ are the original vectors:
N = 50;
xv = linspace(min(x), max(x), N);
yv = linspace(min(y), max(y), N);
[X,Y] = ndgrid(xv, yv);
Z = griddata(x, y, z, X, Y);
contourf(X, Y, Z)
Experiment with it with your data.