\documentclass[11pt,fleqn]{book}

\usepackage{ptext}

\usepackage{xcolor}
\definecolor{mybluei}{RGB}{0,173,239}
\definecolor{myblueii}{RGB}{63,200,244}
\definecolor{myblueiii}{RGB}{199,234,253}

\usepackage{tikz}

\usepackage[explicit]{titlesec}

\usepackage[localise=on]{xepersian}
\settextfont[Scale=1.2]{HM XNiloofar}
\setdigitfont[Scale=1]{HM XNiloofar}

\renewcommand\thechapter{\arabic{chapter}}

\newcommand\chapnumfont{% 
  \fontsize{380}{130}\color{myblueii}\selectfont%
}

\newcommand\chapnamefont{%
  \normalfont\color{white}\scshape\small\bfseries
}

\titleformat{\chapter}
  {\normalfont\huge\filleft}
  {}
  {0pt}
  {\stepcounter{chapshift}%
  \begin{tikzpicture}[remember picture,overlay]
  \fill[myblueiii]
    (current page.north west) rectangle ([yshift=-13cm]current page.north east);
  \node[
      fill=mybluei,
      text width=2\paperwidth,
      rounded corners=6cm,
      text depth=18cm,
      anchor=center,
      inner sep=0pt] at (current page.north east) (chaptop)
    {\thechapter};%
  \node[
      anchor=south east,
      inner sep=0pt,
      outer sep=0pt] (chapnum) at ([xshift=-20pt]chaptop.south)
    {\chapnumfont\thechapter};
  \node[
      anchor=south,
      inner sep=0pt] (chapname) at ([yshift=2pt]chapnum.south)
  {};
  \node[
      anchor=north east,
      align=right,
      inner xsep=0pt] at ([yshift=-0.5cm]chapname.east|-chapnum.south)
  {\parbox{.7\textwidth}{\raggedleft#1}};
  \end{tikzpicture}%
  }

\titleformat{name=\chapter,numberless}
  {\normalfont\huge\filleft}
  {}
  {0pt}
  {\begin{tikzpicture}[remember picture,overlay]
  \fill[myblueiii]
    (current page.north west) rectangle ([yshift=-13cm]current page.north east);
  \node[
      fill=mybluei,
      text width=2\paperwidth,
      rounded corners=6cm,
      text depth=18cm,
      anchor=center,
      inner sep=0pt] at (current page.north east) (chaptop)
    {};%
  \node[
      anchor=south east,minimum width=2in,
      inner sep=0pt,
      outer sep=0pt] (chapnum) at ([xshift=-20pt]chaptop.south)
    {};
  \node[
      anchor=south,
      inner sep=0pt] (chapname) at ([yshift=2pt]chapnum.south)
  {};
  \node[
      anchor=north east,
      align=right,
      inner xsep=0pt] at ([yshift=-0.5cm]chapname.east|-chapnum.south)
  {\parbox{.7\textwidth}{\raggedleft#1}};
  \end{tikzpicture}%
  }
\titlespacing*{\chapter}{0pt}{0pt}{3.5in}

\newcounter{chapshift}
\addtocounter{chapshift}{-1}





\begin{document}
\chapter{فصل}
\section{مقدمه}
\ptext[4]
\subsection{معرفنامه}
\ptext[1-10]
\chapter{فصل بعدی}
\section{قسمت آخر}
\ptext
\end{document}