Read a big csv file with text and data and find specific column in it

I'm using big csv files (870 columns, 6000 rows).

To open and read a file, I use the command :

[fileName,filePath] = uigetfile({'*.csv','Excel Files'});

fid=fopen([filePath,fileName]);

fid = fileread(fileName);

tab = textscan(fid,[repmat('%f',[1,1500])],'Delimiter',';','HeaderLines',7);

In this big file, I need only few columns.

The problem is that the number of rows and columns and the location of a specific data column depend on the file.

That's why I want to find the column I need with its name.

So how to localise in my tab a specific column which has its name in the headerline ?

For instance, I want to skip the 4 first lines, to import the data in the column 'C' under 'DEM' and to create a vector DEM with these data.

Thank you for your help !