var grid = new DataGridView();
            var rows = (from s in grid.Rows.Cast<DataGridViewRow>() select s).ToList();
            var columns = (from s in grid.Columns.Cast<DataGridViewColumn>() select s).Select(x => x.Name).ToList();
            var findText = "valex";
            bool accept = false;

            var result = columns.Where(x => rows.Any(y => y.Cells[x].Value.ToString().IndexOf(findText) >= 0));
            if (result.Any())
                accept = true;