How to solve equation which consist of cell array 6x6, matrices and variables?

I am trying to solve a equation (eq. is written below). I am facing many problems in order to get final result. What i need is S_eff at the end as 6x6 cell array.

How to solve such equations which consist of cell array 6x6, matrices and variables?

Please suggest me best possible ways to solve this equaiton? kindly

Equation is:

S_eff = S_d + (((S_d - S_m) * I6 * (S_d - S_m))/(phi*(I2*S_m*I2' - 1/k_f) - I2*(S_d - S_m)*I2'));
% Here, S_d,S_m, are 6x6 cell array while phi and 1/k_f are single values say phi=0.2, k_f=2
 % I2 =[1 1 1 0 0 0]; 1x6 matrix
 % I6 = I2'*I2; 6x6 matrix