create filedatastore of mat files filtering files by filename pattern

Is it possible to create a filedatastore of mat files filtering files by filename pattern?

So far I got this:

fds = fileDatastore(dir_save,'ReadFcn',@load,'FileExtensions','.mat','IncludeSubfolders',true);
f=1;
while hasdata(fds)
    	disp(num2str(progress(fds)*100)	
        dataarray = read(fds);
        if ~isempty(strfind(fds.Files{f},myPattern))
            %% do somthing
   	end
   	f=f+1;
end

But some mat files I will not be using are really large and therefore slow down the process.

I cannot move all the files to 1 directirory because my directory structure is like:

d01/file1.mat
d01/myPatternFile.mat
d01/othefile.mat
d02/file1.mat
d02/myPatternFile.mat
d02/othefile.mat
etc