How do I use a cell value, assigned to a variable, in a filepath string?

I am trying to open an Excel spreadsheet within a changing location. The variables are the dates and file name:

C:\Reports\2019\09. September 2019\10 September 2019\1. Client reports\Report_20190911.csv

I have tried using variables, referencing to specific cells within a workbook to add the dates that are changing on a daily, monthly, and yearly basis.

Example:

Today - C:\Reports\2019\09. September 2019\10 September 2019\1. Client reports\Report_20190911.csv

Tomorrow - C:\Reports\2019\09. September 2019\11 September 2019\1. Client reports\Report_20190912.csv

I cannot seem to add an image of my referenced excel cells so I will describe it (all the cells are formula driven for the date):

Cell B4 - 10/09/2019 
Cell B6 - 2019
Cell B7 - 09. September 2019
Cell B9 - 10 September 2019

Below is my code:

Sub Client_Reports()

Dim year_ As Integer
year_ = Cells(6, 2)

Dim month_ As String
month_ = Cells(7, 2)

Dim date_ As Date
date_ = Cells(9, 2)

Dim FilePath As String
Dim FileName As String

FileName = "Report_"& Format(Range("B4") + 1, "yyyymmdd") & ".csv"

FilePath = "C:\Reports\year_\month_\date_\1. Client reports\FileName"

Workbooks.Open (FilePath)

End Sub

It searches for C:\Reports\year_\month_\date_\1. Client reports\Report_20190911.csv